Load breaking switches are generally known and are used for interrupting an electric current, in particular by an operator. For each phase of a multiphase power supply they have a rotor which is embodied as a switch shaft segment. A contact arm is pivotally mounted in each case in the rotor and is mounted so as to be pivotable at least between an ON and OFF position about an axis of rotation. At its free end the contact arm carries a contact piece which is movable together with the contact arm.
When the contact arm is in its ON position, i.e. the load breaking switch is switched on, the movable contact piece is in contact with an opposite fixedly arranged contact piece and the current flows through the switch via the two contact pieces and the contact arm. A spring force holds the contact arms in their ON position and presses the contact pieces firmly against each other.
Load breaking switches are designed so that they can be switched off at rated current or also at overload current up to a predefined value, for which purpose a correspondingly high current-carrying capacity is required. The current-carrying capacity is also determined by the contact force with which the contact pieces are pressed against each other. Appropriately dimensioned switch latching mechanisms are used in order to provide the necessary contact force.
The interconnected rotors form the load breaking switch's switch shaft which is actuated by a switch latching mechanism in order to effect the disconnection. The switch latching mechanism is pretensioned by a spring and is unlatched in order to effect the disconnection. After the unlatching all the contact arms are pivoted by the switch shaft against a spring force into their OFF position.